The invention relates to a saw blade sharpening machine provided in particular for saw blades having hard-metal inserts.
In circular saw blades the teeth have to be laterally set off relative to the planar saw blade faces. Such an offset may be obtained by a setting of the teeth or a widening thereof, particularly in the region of the tooth face. Such a widening process is used in particular for saw blades having hard metal inserts. Each tooth carries at its leading side a hard metal piece on which the cutting edges of the tooth are formed. The frontal, forwardly-oriented edge face of the hard metal piece constitutes the tooth face, while its opposite, lateral surfaces define the tooth flanks. The principal cutting edge is defined between the tooth face and the tooth land. In many instances, in manufacturing or sharpening a saw blade, however, not only the principal cutting edge has to be provided or restored but also, the tooth flanks must be given a defined shape.
German Offenlegungsschrift (application published without examination) No. 42 44 180 discloses a grinding machine for the bilateral sharpening of tooth flanks of saw blades provided with hard metal inserts. The grinding machine has two grinding heads, each having a driven grinding disk supported for rotation about an axis. The axes of rotation of the two grinding heads are oriented parallel to one another. Each grinding head is supported on a linear guide whose direction of guidance forms an acute angle with the rotary axis of the grinding spindle. The guiding directions of the two linear guides determine the feed directions with which two sleds are simultaneously advanced to thus simultaneously grind both flanks of the tooth. The two guides are, in turn, carried by guiding sleds, by means of which the grinding heads are adjustable in a direction transverse to the saw blade. Both sleds are driven by a joint threaded spindle and are adjustable so that upon rotation of the threaded spindle the sleds are moved towards or away from one another.
The above-outlined conventional construction requires an accurate alignment of the saw blade with respect to a desired central plane. Such an arrangement may lead to problems particularly when the grinding machine is changed over to saw blades having different blade thicknesses.
German Patent No. 41 20 567 discloses a machine for a multi-stage machining of circular saw blades. The machine has a first grinding device provided with two grinding disks for the tooth flanks and a facing second grinding device having a grinding disk for the tooth land. The two grinding devices may be adjusted independently from one another. The grinding device for grinding the tooth flanks is designed such that the tooth flanks are simultaneously ground and the desired free tooth flank angle may be set according to requirements. The grinding disks are movable back and forth radially of the saw blade with a center sleeve by means of a piston-and-cylinder unit for positioning the grinding disks relative to the tooth flanks.
German Patent No. 41 13 854 shows a similar grinding machine for sharpening-saw blades. This machine too, has a grinding head with two grinding disks supported such that their rotary axes are parallel to one another. The grinding disks are used mainly for grinding the tooth land. The distance between the grinding disks is fixed. The two rotary shafts are supported in a rigid holder which may be pivoted about a pivot axis lying in the plane of the saw blade and which may be displaced in three mutually perpendicular directions. This construction is not adapted for the simultaneous grinding of both tooth flanks of one tooth.